The exemplary embodiments relate to a projector, an image data converting method, and an image data converting program.
A related art projector of a type that forms image lights of plural colors, either simultaneously or in time division, uses at least one transmissive/reflective, multi-/single-panel electro-optical modulator. The related art projector projects projection images according to these image lights onto a projection screen for combined multi-color images to be displayed on the projection surface.
A related art projector includes two types of electro-optical modulators: a single-panel type and a multi-panel type. The single-panel electro-optical modulator includes a single electro-optical modulating element, and outputs image lights of respective color components forming a multi-color image in time division. On the contrary, the multi-panel electro-optical modulator includes more than one electro-optical modulating element, and outputs image lights of respective color components forming a multi-color image simultaneously.
A projector using either the single- or multi-panel electro-optical modulator is subject to a problem in that image lights of respective color components undergo relative displacements in position unless optical paths of all the colors are exactly the same. Such displacements in position are attributed to relative misalignments at least between two components among the illumination device, plural electro-optical modulating elements, and a projection system provided in the projector. In particular, misalignments of the electro-optical modulator with respect to the projection system often become a major cause.
To address or solve this and/or other problems, a relative positional relation of the electro-optical modulator is corrected with respect to, for example, the projection system for each color component. A correction unit used for this purpose includes a correction unit that makes corrections mechanically, and a correction unit that makes corrections like an electric circuit (for example, see JP-A-11-202408 and JP-A-2003-15581).
JP-A-11-202408 discloses a mechanical correction unit that makes corrections by moving optical components mechanically. The principle of this correction unit is described with reference to FIG. 4 of JP-A-1-202408. The correction unit disclosed in JP-A-11-202408 corrects an image position by moving an optical path in parallel using a plate-shaped transparent member that is interposed diagonally in the optical path. Because a relatively large mechanical displacement can be converted to a small change in the optical path, fine adjustments can be achieved.
JP-A-2003-15581 discloses a correction unit like an electric circuit. The principle of this correction unit is described with reference to FIG. 3, FIG. 4, and FIG. 6 of JP-A-2003-15581. The correction unit disclosed in JP-A-2003-15581 makes corrections by moving only a position at which an effective image display is performed in parallel like an electric circuit while maintaining an immovable position by using an electro-optical modulating element larger than the required number of display pixels in size. This configuration enables corrections to be made regardless of mechanical accuracy and stability.
The correction unit disclosed in JP-A-11-202408, however, requires that a correction mechanism has high mechanical accuracy and stability. To be more specific, because pixels in a currently used electro-optical modulating element are of a size on the order of 10 μm, a mechanism that aligns the positions of these pixels needs to be accurate at a degree that allows precise movements on the order of some micrometers. Moreover, there is another problem in that the correction unit needs to have the capability of maintaining the corrected positions for a long period in actual use environments.
However, the correction unit disclosed in JP-A-2003-15581 solves the problem discussed with respect to JP-A-11-202408. To be more specific, the correction unit disclosed in JP-A-2003-15581 does not need a correction mechanism that has high mechanical accuracy and stability. For this correction unit, it is necessary to fix a relative position of the electro-optical modulating element with respect to the projection system mechanically, so that a relative position of the electro-optical modulating element with respect to the projection system remains stable.
JP-A-11-202408 and JP-A-2003-15581, however, have a common problem. That is, there are only two degrees of freedom of correction (two ways of parallel translations along two axial (x-axis and y-axis directions).
To be more specific, the electro-optical modulating element has six degrees of freedom with respect to the projection system in regard to parallel translations along three axial (x-, y-, and z-axes of 3-D coordinate) directions, and rotations about the three axes (rotations using the three axes as the rotational axes). Six degrees of freedom in regard to parallel translations along the three axial directions and rotations about the three axes are defined as follows. That is, let the z-axis be the optical axis direction of the projection system, the x-axis be a horizontal direction orthogonal to the z-axis, and the y-axis be a vertical direction orthogonal to the z-axis. Thus, the three degrees of freedom in regard to parallel translations are parallel translations in the horizontal direction along the x-axis direction, parallel translations in the vertical direction along the y-axis direction, and parallel translations in the depth direction along the z-axis direction. Also, three degrees of freedom in regard to rotations are rotations about the x-axis using the x-axis as the rotational axis, rotations about the y-axis using the y-axis as the rotational axis, and rotations about the z-axis using the z-axis as the rotational axis.
Hence, both of the correction units disclosed in JP-A-11-202408 and JP-A-2003-15581 only allow that corrections be made in only two degrees of freedom, in regard to parallel translations along the two axial (x-axis and y-axis) directions, instead of six degrees of freedom. Thus, no corrections can be made for the other four degrees of freedom. This problem will now be described in detail with reference to the drawings.
FIGS. 15A and 15B are views used to describe corrections that are likely to occur and be corrected by the correction unit disclosed in JP-A-11-202408 or the correction unit disclosed in JP-A-2003-15581. FIG. 15A is a view showing an input image 10 on an electro-optical modulating element 301, and FIG. 15B is a view showing a projection image 10a on a projection surface.
Referring to FIG. 15B, a square, drawn with a thick line, schematically shows a projection image 10a′ used as the reference, and a square, drawn with a thin line, schematically shows the projection image 10a to be corrected. These two squares are of an identical size and parallel translational to each other. In other words, displacements in position in this case are caused only by parallel translations in a direction perpendicular to the optical axis.
Under these conditions, images can be brought into agreement by varying an angle of a plate-shaped transparent member that is interposed diagonally in the optical path, or as is shown in FIG. 15A, by moving a display position of the input image 10 on the electro-optical modulating element 301, in a direction indicated by an arrow 20.
However, in a case where the electro-optical modulating element 301 is misaligned, for example, due to rotations about the three axes (x-axis, y-axis, and z-axis), neither the correction unit disclosed in JP-A-11-202408 nor the correction unit disclosed in JP-A-2003-15581 is able to make corrections.
FIGS. 16A and 16B are schematics showing a projection image when the electro-optical modulating element 301 is misaligned due to rotations about the three axes. FIG. 16A is a schematic showing an input image 10 on the electro-optical modulating element 301, and FIG. 16B is a view showing a projection image 10a on a projection surface. The input image 10 on the electro-optical modulating element 301 is projected onto the projection surface in the form of the projection image 10a, as is shown in FIG. 16B; however, the projection image 10a is deformed into a quadrangle that is not rectangular with respect to the projection image 10a′ used as the reference. This deformation resulted from misalignments of the electro-optical modulating element 301 due to rotations about the three axes. When a projection image is deformed as in this case, it is impossible to superimpose the projection image 10a on the projection image 10a′, used as the reference, no matter how well the display position of the input image 10 on the electro-optical modulating element 301 is moved in parallel.
FIGS. 17A and 17B are schematics showing a correspondence between input images on electro-optical modulating elements 301, 302, and 303 and their respective projection images formed by a projector having the three electro-optical modulating elements 301, 302, and 303 when each of the electro-optical modulating elements 301, 302, and 303 is misaligned due to rotations about the three axes. FIG. 17A is a schematic showing a manner in which input images 10, 11, and 12, respectively, on the electro-optical modulating elements 301, 302, and 303 are projected onto a projection surface 40. FIG. 17B is a view showing respective projection images 10a, 11a, and 12a on the projection surface 40.
In a case like this, where each of the electro-optical modulating elements 301, 302, and 303 is misaligned due to rotations about the three axes, the projection images 10a, 11a, and 12a corresponding to their respective color components are not formed to be rectangles. Hence, an adequate image cannot be obtained even when corrections are made by the correction unit disclosed in JP-A-11-202408 or the correction unit disclosed in JP-A-2003-15581.